The present invention relates to an electrically insulated cable having long-term stability, or high resistance to deteriorated insulation.
Oil-filled cables, cross-linked polyethylene cables, and polyethylene cables are currently used in power transmission and distribution, as well as in power supply to electric machines such as electric precipitators and ion generators. Oil-filled cables exhibit stable characteristics but they often cause oil leakage if not handled with utmost care. Cross-linked polyethylene cables and ordinary polyethylene cables permit easy maintenance and handling, so they are used extensively today, with their voltage levels increasing year by year. The biggest problem with these conventional types electric cables is that they are gradually deteriorated by continued voltage application and breakdown of insulation is caused within a fairly short period of actual service. While numerous studies have been made on the mechanism of deteriorated insulation, no one has ever succeeded in proposing a clear picture for this phenomenon. As a result of various studies made to fill this gap, the present inventors have found an electrically insulated cable having long-term stability and capable of suppressing the deterioration of insulation.